The present invention relates to equipment for handling, processing and cleaning thin panels, including highly flexible sheet members, and more particularly to an improved squeegee roll and squeegee roll arrangement for use in such a thin sheet handling system.
In the art of conveyorized fluidic processing of extremely thin articles, such as flexible electronic circuits, it is desirable not only to have a machine that both transports the thin articles from conveyor roller to conveyor roller with minimal damage and delivers fluid efficiently and effectively to its surface(s), but also to have such a machine whose parts are easily disassembled for maintenance purposes. This fluidic processing includes, among others, circuit feature etching, photo resist image developing, surface treatments and depositions, rinsing and drying.
When the fluid process incorporates delivering the fluid in streams as a sprayed liquid or ducted air over and/or under a conveyorized roller system with the axes of the rollers transverse the direction of desired article travel, it is necessary to mechanically support the thin articles from below and also often from above while attempting to minimize the interference such support tends to impart on the fluid streams. Without sufficient mechanical support, thin articles tend to buckle, wrinkle and/or jam in the conveyor system, causing unwanted machine downtime and loss of product. Towards such minimized interference, narrow rods with wheels are used for mechanical support, rather than solid cylindrical rollers. The spaces between the wheels are intended to allow for more free travel of the sprayed liquid to reach the surface of the article. Often an opposing set of upper rods and wheels are used to keep the articles from lifting and/or buckling.
On either side of the wet area, pairs of squeegee rolls are typically utilized to prevent the processing fluid from dragging out with the thin articles being processed. Such rollers have generally been constructed of a solid core, made of polyvinyl chloride, stainless steel, or titanium, coated with rubber, with each roller weighing eight or more pounds. In the prior known systems, generally only a single pair of upper and lower squeegee rolls was required to contact the thin article as it was carried into and out of the wet area to prevent the processing fluid from escaping. However, in newer high volume systems, such as the RAMJET system which is available from Advanced Chemill Systems, Inc., which was invented by the present inventor and is described in U.S. Pat. No. 5,720,813, which is incorporated herein by reference as if fully set forth, more processing fluid is provided in the wet area at higher pressure, and the processing area is shorter. In order to prevent drag out of processing fluid, multiple pairs of squeegee rollers are required along the conveyor path entering and exiting the wet area. While it is possible to use the known squeegee rollers, this would require a more powerful drive system, and the heavy weight of the known rollers creates more wear on the drive gears typically used.
It is also desirable to provide supports on at least the exit side of squeegee rollers in order to prevent thin articles, such as films of material, from wrapping around the squeegee roller due to the surface tension of the processing fluid on the squeegee roller and the article. Typically grooves are provided in the squeegee roller for the known supports, which take the form of clips. However, such grooves provide an escape path for the processing fluid from the wet section of the equipment because of the loose tolerances required between the clips and the rubber jacketed squeegee roller in order to prevent the rubber from gripping and damaging the clip.